Today, more than ever before, people are very energy conscious and are concerned greatly with energy conservation. Because of the significant energy consumed by automobiles, much emphasis has recently been placed on the development of more efficient and cleaner burning engines, particularly internal combustion engines. While some progress has been made in increasing fuel economy, much of the progress can be attributed solely to the reduction in automobile size.
Development work has been aimed directly at increasing the efficiency of internal combustion engines, and this development work has increased quite dramatically in the past few years because of the increase in energy conservation awareness by the public in general. At this point, it is difficult to properly evaluate the effectiveness of such development work and what progress has been made. It is clear that the ultimate in efficiency has not been reached in fuel consuming combustion engines, and as long as this is the case and energy is in short supply, there will be a need for further research and development in this area.